// 二維碼的生成
 // 1、創(chuàng)建過濾器
 CIFilter *filter = [CIFilter filterWithName:@"CIQRCodeGenerator"];
 // 2、恢復濾鏡的默認屬性
 [filter setDefaults];
 // 3、設置內容
 NSString *str = @"這是一個二維碼的生成結果";
 NSData *data = [str dataUsingEncoding:NSUTF8StringEncoding];
 // 使用KVO設置屬性
 [filter setValue:data forKey:@"inputMessage"];
 // 4、獲取輸出文件
 CIImage *outputImage = [filter outputImage];
 // 5、顯示二維碼
 self.imageView.image = [UIImage imageWithCIImage:outputImage];

/**
 * 根據CIImage生成指定大小的UIImage
 *
 * @param image CIImage
 * @param size 圖片寬度
 */
- (UIImage *)createNonInterpolatedUIImageFormCIImage:(CIImage *)image withSize:(CGFloat) size
{
 CGRect extent = CGRectIntegral(image.extent);
 CGFloat scale = MIN(size/CGRectGetWidth(extent), size/CGRectGetHeight(extent));
 // 1.創(chuàng)建bitmap;
 size_t width = CGRectGetWidth(extent) * scale;
 size_t height = CGRectGetHeight(extent) * scale;
 CGColorSpaceRef cs = CGColorSpaceCreateDeviceGray();
 CGContextRef bitmapRef = CGBitmapContextCreate(nil, width, height, 8, 0, cs, (CGBitmapInfo)kCGImageAlphaNone);
 CIContext *context = [CIContext contextWithOptions:nil];
 CGImageRef bitmapImage = [context createCGImage:image fromRect:extent];
 CGContextSetInterpolationQuality(bitmapRef, kCGInterpolationNone);
 CGContextScaleCTM(bitmapRef, scale, scale);
 CGContextDrawImage(bitmapRef, extent, bitmapImage);
 // 2.保存bitmap到圖片
 CGImageRef scaledImage = CGBitmapContextCreateImage(bitmapRef);
 CGContextRelease(bitmapRef);
 CGImageRelease(bitmapImage);
 return [UIImage imageWithCGImage:scaledImage];
}

NSString *str = @http://www.baidu.com;

#import "ViewController.h"
#import <AVFoundation/AVFoundation.h>
@interface ViewController () <AVCaptureMetadataOutputObjectsDelegate>
/**顯示圖層*/
@property (nonatomic, strong) AVCaptureVideoPreviewLayer *layer;
/**捕捉會話*/
@property (nonatomic, strong) AVCaptureSession *session;
@end
@implementation ViewController

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
 // 二維碼的掃描
 // 1、創(chuàng)建捕捉會話
 AVCaptureSession *session = [[AVCaptureSession alloc] init];
 self.session = session;
 // 2.添加輸入設備(數據從攝像頭輸入)
 AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
 AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:device error:nil];
 [session addInput:input];
 // 3、添加輸出數據(示例對象-->類對象-->元類對象-->根元類對象)
 AVCaptureMetadataOutput *output = [[AVCaptureMetadataOutput alloc] init];
 [output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];
 [session addOutput:output];
 // 3.1.設置輸入元數據的類型(類型是二維碼數據)
 [output setMetadataObjectTypes:@[AVMetadataObjectTypeQRCode]];
 // 4、添加掃描圖層
 AVCaptureVideoPreviewLayer *layer = [AVCaptureVideoPreviewLayer layerWithSession:session];
 layer.frame = self.view.bounds;
 [self.view.layer addSublayer:layer];
 self.layer = layer;
 // 5、開始掃描
 [session startRunning];
}
/**
 * 實現output的回調方法
 */
- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection
{
 // 數組metadataObjects中存放結果數據
 if (metadataObjects.count > 0) {
 // 獲取最終的讀取結果
 AVMetadataMachineReadableCodeObject *object = [metadataObjects lastObject];
 NSLog(@"%@",object.stringValue);
 [self.session stopRunning];
 [self.layer removeFromSuperlayer];
 }
 else
 {
 NSLog(@"沒有掃描到數據");
 }
}